1. Field
Embodiments of the present disclosure relate to an air conditioner and a starting control method thereof, and more particularly, to an air conditioner having a plurality of compressors and a starting control method thereof.
2. Description of the Related Art
As an example of an air conditioner, a heat pump-type air conditioner is an apparatus configured to change a circulation direction of refrigerant in a refrigerant cycle, so that a heating in a winter season along with a cooling in a summer season may be performed.
The heat pump-type air conditioner is provided in a way that, during a cooling operation, a condensation of refrigerant occurs at an outdoor heat exchanger by adjusting a 4-way valve, so that the refrigerant being discharged from a compressor may be drawn into the outdoor heat exchanger, and the condensed refrigerant is decompressed at an expansion valve of an indoor side, and then is evaporated at an indoor heat exchanger to take the heat from the indoor air, so that a cooling may be performed. The refrigerant that is passed through the indoor heat exchanger passes through the 4-way valve, and is drawn into the compressor to be compressed.
During a heating operation, in order for the refrigerant being discharged from the compressor to be withdrawn into the indoor heat exchanger, the 4-way valve is adjusted, so that condensation of the refrigerant may occur at the indoor heat exchanger to supply heat to the indoor air, and thus a heating action is being performed. The refrigerant that is passed through the indoor heat exchanger is decompressed at the expansion valve of an outdoor side, and then is drawn into the compressor again by passing through the outdoor heat exchanger and the 4-way valve.
The heat pump-type air conditioner as such includes two units of compressors each having a different operating capacity to enhance the energy efficiency.
For example, the compressors are designed to be driven in a ratio of a cooling ability of about 6:4. In a case of a first stage driving in which a first compressor having a low operating capacity is being driven, the cooling ability of about 30% to 50% is provided, and in a case of a second stage driving in which a second compressor having a high operating capacity is being driven, the cooling ability of about 50% to 70% is provided. In addition, in a case of a third stage driving in which both the first compressor and the second compressor are being driven, the cooling ability of about 100% is provided.
In general, the first compressor having a low operating capacity is implemented with a variable-capacity compressor capable of varying the operating capacity, and the second compressor having a high operating capacity is implemented with a constant-speed compressor.
Conventionally, in a case of the third stage driving that operates the both of the two units of compressors, the first compressor is started first, and then the second compressor is started for a purpose of decreasing a starting load at the time of an initial start of an air conditioner. As a reference, the starting load of a compressor is increased in a case of the compressor is started when refrigerant is excessively mixed in oil, when a degree of a pressure imbalance occurred between a high pressure side and a low pressure side is severe, when lubricant is not sufficiently supplied to the compressor, or when an input of power has not taken place for a long period of time.
When the second compressor is started, in order to decrease the starting load of the second compressor, which is started after the first compressor, the operating capacity of the first compressor that is already started and driven is decreased.
In the process of decreasing the capacity of the first compressor, which is started and driven prior to the second compressor, to decrease the starting load of the second compressor and of starting the second compressor and simultaneously increasing the operating capacities of the first and the second compressors, the cooling and heating ability of an overall system shows a pattern decreasing and then increasing. Eventually, from the perspective of a user, the cooling and heating speed is decreased.
To prevent the decrease of the cooling and heating speed as such, in a case of simultaneously starting the two units of the compressors, the starting load is increased, and thus the possibility of the starting the compressors failing is increased.